Wafer polishing apparatus having physical cleaning means to remove particles from polishing pad

Abstract

The invention relates to an apparatus for polishing wafers in the fabrication of semiconductor integrated circuits. The apparatus has a turntable on which a polishing pad of polyurethane foam is placed. The pad has a multiplicity of cavities in the polishing surface. In periodically dressing the pad, abrasive grains of diamond fall off the dressing tool, and some of the fallen abrasive grains remain in the cavities in the pad surface even though the pad surface is washed by water. According to the invention the polishing apparatus includes a cleaning device to drive abrasive grains out of the cavities. The cleaning device has a cylindrical body which rotates above the polishing pad. In an embodiment the cleaning device is a rotary brush having a multiplicity of needle-like parts of a synthetic resin on the cylindrical outer surface. The needle-like parts intrude into the cavities in the pad surface and flip abrasive grains out of the cavities. In another embodiment the cleaning device has an elastic covering on the cylindrical body. The elastic covering is squeezed into the cavities to temporarily close the opening of the cavities and reduce the air pressure in the cavities. When the elastic covering leaves the cavities a rush of the air into the cavities drives diamond grains out of the cavities.

Dependencies are inferred from the claim text.